← All parts of this equation

Equation 93 · Part 1 · The Atlas That Refuses to Close

Symbol x

xx
xx

What this part means

the preselect a spin-one-half system along.

Its job in the formula

x is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Where the article explains it

Preselect a spin-one-half system along x , |ψ\psi⟩\rangle = 12(∣↑⟩+∣↓⟩)\tfrac{1}{\sqrt2}(|{\uparrow}\rangle+|{\downarrow}\rangle) , and postselect along y , |f⟩\rangle = 12(∣↑⟩+i∣↓⟩)\tfrac{1}{\sqrt2}(|{\uparrow}\rangle+i|{\downarrow}\rangle) .

The passage around this formula

An exact two-level calculation shows how far this can depart from the intuitive picture. Preselect a spin-one-half system along x , |ψ\psi⟩\rangle = 12(∣↑⟩+∣↓⟩)\tfrac{1}{\sqrt2}(|{\uparrow}\rangle+|{\downarrow}\rangle) , and postselect along y , |f⟩\rangle = 12(∣↑⟩+i∣↓⟩)\tfrac{1}{\sqrt2}(|{\uparrow}\rangle+i|{\downarrow}\rangle) . Then ⟨\langle f|ψ\psi⟩\rangle = 12(1−i)\tfrac12(1-i) and ⟨\langle f|σz\sigma_z|ψ\psi⟩\rangle = 12(1+i)\tfrac12(1+i) , so the weak value of σz\sigma_z is

Read this part in the article →

Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

Open the illustrated variables: a letter stands for a value guide →

See this notation across published equations →

Sources cited in the article section

These citations provide research context; check each source for the exact claim it supports.